In the prior art, the use of copper chromite catalyst is described for its catalytic activity for the hydrogenation of dicarboxylic acids or dicarboxylic acid esters and/or anhydrides. Most of these patents use copper chromite catalysts containing the combination of one or more mixed oxides of copper, zinc, barium, aluminum of varying composition. Such catalysts have been procured from the catalyst manufacturers. U.S. Pat. No. 4,810,807, (1989) describes the hydrogenation of butyl ester of maleic anhydride using a copper chromite catalyst commercially available from United Catalysts (No. T-2107). The patent also mentions the use of a cocatalyst consisting of oxides of copper, chromium and barium available from Harshaw/Filtrol (No. 1107T).
The U.S. Pat. No. 4,584,419 (1986) and the International Patent W086/03189 (1986) use the most preferred catalysts which contain copper and chromium together in a range of 60-62% and no more than approximately 15% by weight of stabilizers (i.e. barium and/or manganese). The method of catalyst preparation is not clearly understood from these literature, however, the reduction of the copper chromite has been described in International patent WO 86/03189 (1986).
Recently, Castiglioni et al. (Chemistry and Industry, 5 Jul. 1993,) have reported preparation of copper chromite catalyst by using sodium carbonate as precipitating agent. Also, the copper chromite catalysts mentioned in this paper do not contain aluminum and zinc together, and the side products such as butanol etc. obtained are in high quantities.